Model WinstelCast for P. infestans
Environmental: Temperature, relative humidity. Calculated: Daily average, minimum and maximum temperatures, hours of temperatures greater than 10°C and relative humidity greater than 90%.
This model is composed of two phases. Phase 1 predicts infection, which is predicted after the following requirements are met: After the daily average temperature is between 10°C and 23° C and then 10 hours or more of temperatures greater than 10° C and relative humidity greater than 90% occur (such periods are considered to be the same as leaf wetness). Phase 2 sets criteria for pathogen growth. Phase 2 occurs when the maximum daily temperature for two consecutive days is between 23°C and 30°C. Phase 2 must occur at least 24 hours but not later than 10 days after phase 1.
Treatment should be initiated, when phase 1 occurs and is followed by phase 2. Be aware that this model was developed for early potato varieties! Developed by Winstel, K. 1993. Kraut- und Knollenfaule der Kartoffel eine neue Prognosemoglichkeit-sowie Bekämpfungsstrategien. Med. Fac. Landbouww. Univ. Gent, 58/3b. In the graph the two phases are shown. First the infection (temperature between 10°C and 23°C and then 10hour of relative humidtiy more than 90%) on the 17th of June and then phase 2 (propagation hours) with maximum daily temperature for two consecutive days between 23°C and 30°C.